Carl hoffmann



' sulfuric acid of 66 Baum.

UNITED STATES PATENT OFFICE.

CARL HOFFMANN, OF HClCHST-ON-THE-MAIN, GERMANY, ASSIGNOR TO THE FARBWERKE, VORMALS MEISTER, LUGIUS & BRUNING, OF SAME PLACE.

GREEN DYE AND PROCESS OF MAKING SAME.

SPECIFICATION forming part of Letters Patent No. 615,485, dated December b, 189a.

Application filed December 28, 1897. Serial No. 664,081. ($pecimons.)

green dyestuffs may be obtained from metaoxysulfonic acids of the benzene or napththalene series, having the general formula:

alphyl(2)SO H(SO H) OR They, therefore, are dyestuffs which contain a sulfo group linked in ortho position to the carbon of the methane as well as an alkyloxyl in para position. The new dyestuffs are fast to alkali in contrast to those which have a hydroxyl instead of an alkyloxyl.

The method for the manufacture of these new dyestuffs consists in condensing tetra-alkyl paradiamidobenzhydrol-for example, tetramethyl-tetraethyl, or dialkyldibenzylparadiamido benzhydrol, with metaalkyloxysulfonic acids, such as meta-methoxybenzenesulfonic acid, 1.3 methoxy-napthalene sulfonic acid, 1. 3. 6 methoxynapthalene disulfonic acid, and oxidizing theleuco compounds thus formed. If a monosulfonic acid be employed, a further sulfonation is necessary either before or after oxidation of the leuco compounds.

The metaitlkyloxysulfonic acids maybe obtained from the alkali salts of the corresponding oxysulfonic acids by the action of methyl or ethyl sulfate of sodium.

Example: A mixture of ten parts,by weight, of symmetric dialkyldibenzylparadiamidobenzhydrol, and five parts, by Weight, of the sodium salt of metaalkyloxybenzene sulfonic acid are introduced, with stirring and gentle cooling, into fifty parts, by weight, of As soon as the yellow color of the solution has disappeared it is poured on ice, filtered oif, and well washed with water.

For the sulfonation the dried leuco body is dissolved in five times the quantity of fuming sulfuric acid of twenty per cent. As soon as a sample of it is completely soluble in water the whole is poured on ice and neutralized with lime.

For the oxidation of the easily-soluble calcium salt of the leucosulphonic acid obtained by evaporation of the solution filtered from sulfate of lime ten parts, by weight, of this salt are dissolved in about three hundred parts, by weight, of water and treated with the calculated quantity of diluted sulfuric acid and peroxid of lead paste of ten per cent. Thereupon it is filtered from the lead sulfate and the dyestufi solution evaporated to dryness.

The dyestuff forms a dark copper red brilliant substance soluble in water with a green color, .almost insoluble in alcohol, and easily soluble in concentrated sulfuric acid with a brown-yellow color. The aqueous solution turns light green on addition of an excess of mineral acid, but eeps its original color on addition of caustic soda-lye in the cold. It

dyes wool in an acid-bath a green shade fast subsequent sulfonation and oxidation, fdrm- In testimony that I claim the foregoing as ing a dark copper-red. brilliant substance, my invention I have signed my name in pres- 1o soluble in Water with a green color, soluble ence of two subscribing Witnesses.

With difficulty in alcohol, easily soluble in CARL HOFFMANN eoncentrated sulfuric acid with a brown-yellow color, and dyeing wool in an acid-bath a lVitnesses:

green shade fast to alkali, substantially as HEINRICH HAHN, set forth. ALFRED BRISBOIS. 

